This update should improve FPS at the cost of more total workload and a slight update delay.
Originally I tasked Windows copy the window contents directly into texture memory on the main thread. This turned out to have a non-negligible cost on frame times once you are in the hundreds of FPS. I.e. a drop from 260 to 160 FPS was likely when turning the overlay on. Now a separate thread is grabbing the window contents into an intermediate buffer of the same format as the texture while the main thread only does a plain memory copy to update the texture when the ReShade overlay is drawn.
A slight delay of 1 frame may be noticed between the actual LiveSplit window and the overlay due to those deferred updates.